The idea is to allow the C++ layer to run arbitrary scripts
as the main script. This paves the way for
- cctest of the execution of Node.js instances
- Earlier handling of per-process CLI options that affect
execution modes (those usually do not make sense for the
embedders).
- Targets like mkcodecache or mksnapshot.
Also moves the handling of `_third_party_main.js` into C++.
PR-URL: https://github.com/nodejs/node/pull/25474
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>